An investigation is underway to determine the cause of a fire that destroyed a vacant building in Plainfield.

There were numerous squatters seen exiting the property on East 3rd Street while the building was up in flames, according to the Plainfield Fire Department. No injuries have been reported among the firefighters.

Plainfield Fire Department says the fire started shortly after 2 a.m. Severe conditions had them escalate the response to three-alarms, bringing in mutual aid from surrounding towns.

Springfield firefighters say their Ladder 1 helped for three and half hours.

Union helped out as well in the Queen City.

Westfield Fire Department says they were cleared from the scene at 5:30 a.m.

The New Jersey State Fire Marshall is investigating. Plainfield Fire Department says search and overhaul operations were made to ensure safety and to assess any further hazards. The cause of the fire is under investigation.

The Fire department is asking everyone to avoid this area of East 3rd Street while emergency operations continue.